Right click on your desktop and pick properties.
Apperance tab
Windows and Buttons:
Windows XP Style
Color Scheme:
Default (blue), Olive Green, or Silver.
Pick silver, hit ok.
Olive Green is quite possibly worse than the Blue (it does have the benefit of matching the start button, but that's just cuz it looks like someone puked on your whole desktop instead of just the one corner), but the Silver is pretty nice except it doesn't change the startmenu button's colour.